1. Field of the Invention
The present invention relates to the field of display technology, and in particular to a method for manufacturing a low-temperature polycrystalline silicon (LTPS) thin-film-transistor (TFT) substrate structure and a structure of a LTPS TFT substrate.
2. The Related Arts
LTPS TFT has valuable and potential uses in the field of high definition display devices of active matrix liquid crystal display (AMLCD) and active matrix organic light emitting diode (AMOLCD).
Compared to the amorphous silicon (a-Si) technology, LTPS TFT has a relatively high mobility and excellent device stability. The mobility of LTPS TFT may be as high as tens to hundreds cm2/Vs, which satisfy the needs of high-definition AMLCD and AMOLED displays. Thus, a LTPS display has a faster response speed and shows various advantages including high brightness, high resolution, and low power consumption. In addition to being used as a pixel switch, LPTS TFT is also used to construct a peripheral driver circuit to provide an integrated system on a chip.
Excimer laser annealing (ELA) is a technique of irradiating short period pulses of laser to a surface of amorphous silicon to have it melt and recrystallize. Driving an AMOLED needs a switch TFT and a driving TFT, of which the driving TFT must have consistent electrical property in order to provide a consistent power of driving for preventing inhomogeneity of color displayed in a displaying process. This requires the crystal grains of polycrystalline silicon in an area associated with the driving TFT must show improved homogeneity and the size of the crystal grains must be larger.
However, the state-of-the-art ELA crystallization techniques do not provide an effective control of grain homogeneity and grain size. Consequently, the crystallization shows poor distribution over the entire substrate, leading to poor consistency of polycrystalline silicon grains in the area associated with the driving TFT and relatively small grain sizes, making the consistency and stability of electrical property of the driving TFT. As such, poor image quality may readily occur.